Interlocked switch and circuit breaker unit



May 22, 1956 H. E. scHLEicHl-:R 2,747,047

INTERLOCKED SWITCH AND CIRCUIT BREAKER UNIT Filed March 23, 1954 3 Sheets-Sheet l figg;

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May 22, 1956 H, E SCHLElCHER 2,747,047

INTERLOCKED SWITCH AND CIRCUIT BREAKER UNIT Filed March 23, 1954 5 Sheets-Sheet 2 May 22, 1956 H. E. SCHLEICHER 2,747,047

INTERLOCKED SWITCH AND CIRCUIT BREAKER UNIT Filed MaFCh 25, 1954 5 Sheets-Sheet 3 INVENTOR.

///5 ATTOR NE YS,

United States Patent INTERLOCKED SWITCH AND CXRCUIT BREAKER UNT Harold E. Schleicher, West Hartford, Conn., assigner to The Arrow-Hart & Hegeman Electric Company, Herttord, Conn., a corporation of Connecticut Application Marcil 23, H54, Serial No. 13,t35

20 Claims. (Cl. 20th-50) In many prior electric circuit making and breaking devices, the same set of contacts is required to serve for normal opening and closing of the circuit and also to serve for overload circuit breaking duty. Since the circumstances and conditions of these two services are different, the ideal for one is not the ideal for the other. Overload actions may shorten the life of the contacts for normal switching and normal wear in switching may impede action where urgently needed on overload.

This invention relates to an interlocked switch and circuit breaker unit wherein the switch is used for normal opening and closing of the circuit by hand while the circuit breaker is provided for opening the circuit under overload conditions. More particularly, the invention relates to an interlocked switch and circuit breaker unit wherein the circuit-breaker contacts cannot be reengaged while the switch is in closed position, but wherein it is necessary rst to operate the switch to open circuit position in order to allow the circuit breaker to be reclosed.

lt is sometimes desirable to have normal opening and closing of the circuit with a snap action of the switch contacts. Since the reclosing of the circuit-breaker contacts is normally a slow action, it is therefore necessary to provide for interlocking the circuit breaker and switch mechanisms to require the nal closing of the circuit to be by the switch contacts rather than by the circuitbreaker contacts.

It is also desirable to have the switch contacts of rugged construction, such as butt contacts, which stand up under hard usage as when it is necessary repeatedly to open and close a circuit carrying currents necessary to the running of heavy machinery.

lt is also desirable to have provision to test the operability of the circuit breaker mechanism since the circuitbreaker contacts might be stuck or welded closed without that condition becoming known. That could occur because the normal operation of the opening and closing of the circuit is by manual operation of the switch conacts which are in series with the circuit-breaker contacts. Thus, a permanent sealing of circuit-breaker contacts, which are not visible, would not be otherwise indicated by any irregularity of function of the circuit breaker.

Therefore, it is an object of the invention to provide an improved unit including two separate interlocked mechanisms which act respectively for normal circuit opening and closing and for overload opening of the circuit.

Another object is to provide, in a unit of the above type, switching means wherein the contacts which control the normal opening and closing will snap closed and open.

Another object is to provide in such a combination, provision to prevent reclosing of the circuit breaker when the switch is closed.

Another object is to provide means in such a combination for testing the operability of the circuit breaker mechanism, as a safety feature, to give assurance of normal functioning.

A further object is to provide in a device possessing the foregoing characteristics, an arrangement of elements which will permit straight-through wiring.

A further object to provide in a combination of the foregoing type, an arrangement which will not interfere with the commercial needs for interchangeability of the overload-responsive heater elements for the various lines the circuit.

A further object is to provide a unit having the foregoing characteristics which is fully enclosed to keep out lint and dirt and whose parts are formed for minimum eiiect by vibration and shock, so that the unit will be particularly useful on machines and in places where both or one those conditions exist.

Another object of the invention is to provide a device having the foregoing characteristics which constitutes a single unit permitting interchangeability of one unit for another without disturbing the wiring of the whole installation.

Gther objects and advantages of the invention will become apparent as it is described in connection with the accompanying drawings.

in the lrawings:

Fig. l is a plan view of a device embodying the invention with certain parts removed or broken away ad- ,acent the thermal elements.

2 is a longitudinal section View taken along line 2-2 ci -Fig. l.

Fig. 3 is a bottom view of the inside of the cover when removed from the -device.

Fig. 4 is longitudinal elevation view taken along line @--f of Fig. l. K

Figs. 5 and 6 are exploded perspective views of parts of the thermal release mechanism and interlocking mechanisrn respectively e loved in the invention.

Fig. 7 is a pian view of the base and parts contained therein with the cover removed.

Fig. 8 is an exploded perspective view of the operating mechanism of the s "tc" in association with certain parts oi the circuit brealr mechanism.

The invention is conveniently mounted in a generally rectangular two part molded insulating housing. The

i ti the housing is hollowed out in its surface for p or the elements which make up the invention. The cover portion is hollowed out to receive part ci the elements and also to it over the base and to cooperate therewith so that the operating mechanism and the switch and circuit breaker contacts are entirely enclosed. Pihe invention is shown as applied to a three-wire circuit in which thermally-responsive means for causing the ope or" the circuit on overload conditions are located two of the outside lines.

The invention co Ecrises in general a switching mechanism a circuit crea ing mechanism, each of which is operable se e 'ateiy, out between which there is an irtetlockirU arrangement to prevent the reclosing of the 4't 1xcre g contacts and mechanism while the switching contacts and mechanism remain in closed-circuit position.

The sw the heus' rg contacts, The being shown only npie oi the invention when user to c' :trol circuit. The xed contact buttons i oi each air are mounted on stamped sheet metal terminal a-lixed on he top oi' the cover and seated in d in one end thereof. The terminals are han'. c' so that the ends on which the bm mounted extend through apertures e inner ends oi the terminalreceiving recesses is located at one end of plut y of pairs of butt rs, is not s` .iicann three The movable contact buttons 18C are each mounted on a tiexible L-shaped stamped sheet metal strip 18 which extends through an aperture 19 in the floor of the base and has its foot 18a secured to the underside of the base. Each foot is also engaged with the bar portion 2Gb of a combined connector bar and xed contact of the switching mechanism. These bar portions are flat and run along the bottom of the base to apertures therein, through which the contact portion 20c is bent to extend up into the housing.

For operating the movable switch contacts, a cam shaft 22 is journaled in a pair of stamped sheet metal end brackets 36a, Stib iixedly mounted at opposite sides of one end of the base. insulating wedge-shaped cam members 24 are iixedly mounted at spaced points along the cam shaft in position to engage and ex the movable contact-carrying members i8 against their normal bias into engagement with the iixed contacts.

Also journaled in the end brackets, parallel to and above the cam shaft, is an operating shaft 26. Atiixed to each end of the operating shaft outside the end brackets is an upper corner of a triangularly shaped stamped sheet metal actuating plate 32a, 3211. Pivotally connected to another upper corner of each of the actuating plates is one end of an operating sheet metal bar 34a, 34]?, on the other end of which is mounted an insulating button Attached to an out-turned lug 33 at the lower corner of the actuating plate is the lower end of a coiled tension over-center spring 35 whose upper end is attached to an out-turned lug 33a, 38b overlying the top of the bracket and extending from a cam shaft actuating member 39a, 39h. The cam shaft actuators 39a, 39h are stamped sheet metal parts affixed to the cam shaft near its ends inside and adjacent the brackets 32a, B2b. Arcuate slots are provided in the cam shaft actuators through which the operating shaft 26 passes so that the actuators 39a, 39b can move relative to the shaft.

It is necessary that the depression of the two buttons shall move the cam shaft in different directions to cause engagement and disengagement of the contacts. To that end the cam shaft actuators 39a 39h and actuating plates 32a, 32b which are respectively identical, are mounted facing in opposite directions, with the result that the pivotal connections of the operating or button bars 34a, 34h are on opposite sides of the plane of the operating and cam shafts 22, 26. Hence, when one button is depressed, it tends to move the actuating meinber and operating shaft in one direction and to snap the parts to open-circuit position while when the other button is depressed, it does the opposite. Since the brackets are faced oppositely, the stop lug Sib on one serves to stop the motion of the mechanism in one direction when the shaft operating plate 32b abuts it, while the lug on the other bracket stops the motion of the mechanism in the other `direction in the same way.

A mechanism and separate set of contacts are provided for breaking the circuit on occurrence of an overload. This set of circuit breaking contacts separate independently from the contacts 14, 18e of the switching mechanism just described. However, the resetting of the circuit breaking mechanism is conditioned by interlocking means upon the switching mechanism being in open-circuit position.

The circuit breaking mechanism is located near the opposite end of the base from the switching mechanism. It comprises a square circuit-breaker shaft 40 located transversely in the base in parallel relation to the shafts of the switching mechanism. The ends of the circuitbreaker shaft which are round are seated in journal or bearing recesses 42 in the top edge of the walls of the base. Mounted upon the circuit-breaker shaft is a square insulating sleeve 44. Mounted upon the sleeve at spaced points are fabricated bridging-contact wafers, each comprising pairs of identical conductive iiexible arms, designated generally by 46, extending diametrically and facing one another so as to be able to engage on opposite sides of flat fixed contacts, e. g. 26C and 4'7. Fiber insulating discs 49 are aiixed against the outside of the bridging contact arms to snuff out the arc. Since the structure of the bridging contacts and the fiber discs is conventional, it need not be further described.

At a convenient position intermediate the ends of the circuit breaker-shaft, a latch disc 50 is mounted on the square sleeve 44. This disc may conveniently be made from sheet metal with a segmental cut formed in its periphery extending about 90 around the circumference providing at its opposite ends shoulders 52, 54. One shoulder 52 is adapted to be engaged by a finger 61 extending from a latch member 60 as hereinafter described while the other shoulder 54 is adapted to be engaged by the lower end or foot 7l of an interlocking member 7has hereinafter described. Extending laterally from the latch disc, is a short pin 56 in position to be engaged by the lower end of a reset bar or button 5d. The reset bar may be of insulating material and extend perpendicularly upward through the cover with an offset or shoulder 59 provided in one side thereof to engage with a similar shoulder 10s inside the cover, thus to prevent the button from moving entirely outwardly through the cover after the device has been assembled.

in order to bias the circuit-breaker shaft into open circuit position, a round sleeve 86 is provided on one end of the shaft, around which is coiled a tension spring 82. One end 81 of the spring extends downwardly into and engages with the side wall 12s of a recess in the base wherein the spring is located. The other end 83 of the spring is adapted to engage with one side of a laterally bent lug S4 from the periphery of a spring tension disc 85. This spring tension disc 85 may be stamped conveniently from sheet metal with a square aperture in its center so as to iit slidably on the square shank of the circuitreaker shaft near its end. With the end 83 of the spring pressing on lug 84, the spring constantly urges the disc 85 and shaft 4@ in a counterclockwise direction (as viewed in Figs. 2, 4, 6 and 8 of the drawings).

The bridging circuit breaker contacts 46, of which there will be three in the embodiment illustrated, normally connect bottom fixed circuit breaker contacts 20c (of which there are also three, mounted in the iioor of the base as hereinhefore described) to top fixed circuit breaker contacts 47', 472 or 473. These top contacts are each bolted to the inside surface of the cover in positionV to lie directly over one of the bottom circuit breaker contacts. The top contacts comprise flat fingers bent down at right angles from stamped metal bars 4S', 4%2, 4&3 which extend longitudinally of the cover, the Outside ones 48 and 483 extending toward the switch mechanism While the middle one 482 extends in the opposite direction. The fixed and movable circuit breaker contacts of each set are located in one plane, the planes of the three sets being parallel.

Bolts 45', 452, 453 pass through the cover and serve to secure the bars and contacts 47, 48 (designated generally) to the cover and also serve to electrically connect those parts to the stamped metal terminal plate 75 mounted in recesses in the top of the cover. Connecting these terminal plates 75 to stamped metallic wire-terminal plates 76', 763, secured in recesses at the end of the cover, are coiled resistance heater elements 77 which are each attached at their ends by screwbolts lto the terminal plates 75', 76 and 753, 763 respectively.

On overload the heat from these heaters, passing through a metal shield plate 78, aiects one or another of similar bimetallic cantilever strips 79, each attached at one end to the cover under the terminals 76', 763. On heating, the affected bimetal iiexes, its unattached or inner end engaging and causing pivoting of the latch member 6i).

The thermally-responsive member 60 is a fabricated unit comprising a sheet metal part stamped in U-shape through the parallel legs 62 of which pass a long pivot pin 63 paralleling the transverse midportion of the member. Mounted on the pivot pin and connected to the member 60 iiat against each of the inside surfaces of the legs 62 is a flat insulating cam 64, the bottom or inner surface of which is positioned to be pressed upon by the flexing bimetal strip 79. The cam pieces are slotted to embrace the transverse portion of the member 60, so as to be caused to turn therewith about pivot pin 63. The ends of the pivot pin 63 seat in bearing recesses or seats formed in the underside of the cover. In order to hold the ends of the pivot pin 63 in their seats, a iiat stamped sheet metal L-shaped securing bar 68 has its long leg overlying the midportion of the pin and secured in that position by a screw 68s passing through the short leg into the cover.

The latch finger 61 extends laterally from the midportion of the member 60 in a direction to overlie the periphery of the latch disc Si). The finger is biased into engagement with the periphery of the latch disc by a small coiled compression spring 65 seated in a small bore or recess in the underside of the cover and pressing upon the top surface of the finger 61.

As the bimetallic members or one or the other of them iexes, the tip or tips of the affected bimetal will press on an insulating cam 64, causing the member 6i) to pivot counterclockwise (referring to Fig. 4) about the pin 63. The linger 6i is thus lifted from the latch disc 32 interrupting its latch action. circuit breaker spring 82 causes the circuit breaker mechanism to rotate counterclockwise (Fig. 4) disengaging the bridging Contact d6 from the tixed contacts 20c and i7 (all designated generally). As this occurs, the trip lever biasing spring 73 moves the foot '7l of the trip lever into the cut in the latch disc 5G behind the shoulder 54. That prevents resetting by the return of the disc and circuit breaker mechanism to their former position, until the interlocking lever foot 71 is moved from the shoulder 34.

To unlatch the circuit breaker mechanism and permit its resetting, a fiat releasing finger 90 of generally arcuate form is xedly mounted upon the cam shaft 22 of the switch mechanism in the same plane as the interlocking lever and is so positioned about the axis of the shaft that when the shaft is in switch-open position, the releasing tinger will press against the head end 72 of the interlocking lever and cause it to pivot clockwise, thus disengaging its foot 71 from the latch disc. Thus when the. switch is open, the reset button 58 of the circuit breaker can he depressed, causing the circuit breaker to rotate clockwise and causing reclosing of the circuit breaker contacts. On return to closed-circuit position, the latch linger el of the thermally responsive member drops befhind the shoulder 52 holding the circuit breaker in that. position. Now the switch can be closed by pressing the start button. That moves the cam shaft 22 counterclockwise in Fig. 4, thus rotating `the releasing finger 90 away from the head 72 of the interlocking lever and. freeing that lever for operation to latch the circuit breakerl open upon the next tripping of the circuit breaker mech anism.

It will thus be seen that so long as the switch mech-l anism remains closed, the circuit breaker mechanism cannot be reset, i. e. moved from open to closed-circuit position. Only after the switch contacts and mechanism have been moved to open-circuit position is the interlocking means moved to permit the circuit breaker mechanism to be reset.

In order that it shall be possible to test the operation. of the circuit breaker mechanism and the latch member, a test pin 67 extends through the cover over a lug 69 lateraily extending from the opposite side of the midportion of the member 60 from the nger 61. A coiled tension spring 66 presses upon this lug and is coiled Thereupon the bias of the CFL iii

around the inwardly extending end of the test pin, engaging against a shoulder formed by an enlargement 67 thereon. This enlargement also prevents the pin from being pressed up through the cover by the spring 66.

The path of the outside-lines current through the device is typically as follows: From terminal 15 through butt contacts le, 18C, movable contact strip 18, bus bar and circuit breaker contacts 20c, 46, 47', bolt 45' heater coil 77 to wire terminal 76 The path through the neutral line is the same except that from circuit breaker contact and oar 482, the connection is through a bolt directly to wire terminal 762.

From the foregoing, it will be observed that `the switching mechanism may be operated manually to normally open and close the circuit; but that after the circuit has been opened upon overload as a result of the action of the thermaliy responsive latching means, the circuit may not be reclosed by the closing of the circuit breaker contacts. The closing of the circuit breaker contacts cannot be accomplished so long as the switch contacts remain closed. The switch mechanism must tirst be moved into open-circuit position before the circuit breaker mechanism can be reset. This ensures that the closing of the circuit shall always take place by action of the switch contacts which operate both between open and closed positions with a snap action. The life of `the device is thus prolonged by reason of the ordinary circuit opening and ciosing always taking place between the butt type contacts of the switch mechanism.

it will also be observed, particularly by reference to Figs. l, 2 and 4, that the parts of the unit are fully cnclosed, thus preventing dust and lint from entering as is particularly likely in textile mills. Moreover, the use or" the particular forni of circuit breaker contacts 46a, 46h and associated disc L59 and circular latching disc Si) together with switching contact that are biased closed, enables usage of the device on machines and under conditions where there is apt to be considerable vibration Without danger of accidental Contact separation.

Many modications within the scope of the invention will occur to those skilled in the art. Therefore, I do not limit the invention to the specific form and detail of the embodiment in connection with which it is illustrated and described.

What is claimed is:

l. Switching mechanism comprising contacts, manu ally operable means to cause closing and opening of said contacts, in combination with circuit breaker mechanism comprising contacts adapted to be opened and closed, current responsive means to cause operation of said circuit breaker contacts automatically on occurrence of predetermined eonditions in the circuit, manually operable means to restore said circuit breaker contacts to the position occupied before automatic operation, and mechanical interlocking means between said switch and circuit breaker mechanisms preventing said restoration of said circuit breaker contacts while the position of said switch contacts remains unchanged.

2. Switching mechanism comprising contacts, manually operable means to cause closing and opening of said contacts, in combination with circuit breaker mechanism comprising contacts adapted to be opened and closed, current responsive means to cause opening of said circuit breaker contacts automatically on occurrence of predetermined conditions in the circuit, manually operable means to reclose said circuit breaker contacts, means automatically locking said circuit breaker contacts open on occurrence of automatic operation of said circuit breaker, and means interconnecting said locking means with said switch mechanism to disable said locking means on move ment of the switching mechanism to open said switch contacts.

3. Switching mechanism comprising contacts, manually operable means to cause closing and opening of said contacts, in combination with circuit breaker mechanism comprising contacts adapted to be opened and closed, current responsive means to cause operation of said circuit breaker contacts automatically on occurrence of predetermined conditions in the circuit, manually operable means independent of said manually operable switchcontact-operated means, to reset said circ-'uit breaker mechanism, and mechanical interlocking means between said switch and circuit breaker mechanisms preventing resetting of said circuit breaker mechanism until said switching mechanism has been operated from the position it occupied when the circuit breaker mechanism operated automatically.

4. Switching mechanism comprising contacts, manually operable means to cause closing and opening of said contacts, in combination with circuit breaker mechanism comprising contacts adapted to be opened and closed, current responsive means to cause operation ot said circuit breaker contacts automatically on occurrence ot pre-I determined conditions in the circuit, manually operable means to reset said circuit breaker mechanism, and mcchanical means between said switch and circuit breaker' mechanisms operable automatically on automatic operation of the circuit breaker mechanism to lock said circuit breaker mechanism in automatically-operated position, and means operable on subsequent operation of the switch mechanism to disable said locking means.

5. The combination claimed in claim l in which the switch mechanism includes butt type contacts, and snap acting means to cause opening and closing of said butt contacts.

6. The combination claimed in claim 3 in which the switch mechanism includes butt type contacts, and snap acting means to cause opening and closing of said butt contacts.

7. The combination claimed in claim 1 in which the circuit breaker mechanism is normally biased, and latching means holding said circuit breaker mechanism against said bias, said latching means being operable by said cur rent responsive means.

8. Switching mechanism comprising contacts, manuallyoperable means to cause closing and opening ot said contacts, in combination with circuit breaker mechanism comprising contacts adapted to be opened closed, current responsive means to cause operation of said circuit breaker contacts automatically on occurrence of predetermined conditions in the circuit, manually operable means to reset said circuit breaker mechanism, mechanical interlocking means between said switch and circuit breaker mechanisms, means movable concomitantly with said circuit breaker contacts engaging said interlocking means to latch said circuit breaker mechanism in auto-operated position, and means movable concomitantly with said switch operating means to de-activate said interlocking means in one position of said switching means.

9. The combination claimed in claim 8 in which the interlocking means comprises a pivoted lever one end ot which is engageable with the means movable with the circuit breaker, the other end being engageable with the means movable with the switch operating means.

l0. The combination claimed in claim 9 in which the switch operating means includes a rockable shaft, and the means movable with the switch operating means is mounted on said rockable shaft.

11. The combination claimed in claim l() in which the 8 latching means movable with the circuit breaker comprises a notched disc.

12. The combination claimed in claim 8 in which the interlocking means comprises a pivoted lever one end of which is engageable with the means movable with the circuit breaker, thte other end being engageable with the means movable with the switch operating means and in which the latching means movable with the circuit breaker comprises a notched disc.

13. The combination claimed in claim 4 in which the circuit breaker mechanism includes a notched disc cooperating with said means to lock the circuit breaker.

14. The combination claimed in claim 13 in which the current responsive means includes a latching element engaged with said notched disc and disengaging therefrom on response to said predetermined current conditions.

15. The combination claimed in claim 4 in which the automatic circuit breaker operating means includes a latch disc, and a latching element engaged with said disc and disengaging therefrom on response to said predetermined current conditions.

16. The combination claimed in claim 3 having manually operable means to actuate said current responsive means irrespective of current passage therethrough to test the operation of the latter.

17. The combination claimed in claim i3 in which the current responsive means includes a latching element engaged with said notched disc and disengaging therefrom on response to said predetermined current conditions and manually operable means engageable with said latching element to disengage it from said disc for testing the operation of said automatic operating means.

18. The combination claimed in claim 3 and a two part housing enclosing the same, said automatic operating means of the circuit breaker mechanism including a latching element and thermally responsive means to move said latching element both mounted in one portion of the housing, said circuit breaker and switch mechanisms both being mounted in the base portion of the housing.

19. The combination claimed in claim 3 and a two part housing enclosing the same, said switch mechanism being mounted entirely in the base portion ot the housing.

20. The combination claimed in claim 3 in which the switching contacts and the circuit breaking contacts each include a movable contact and a fixed contact, a two part housing enclosing said combination, a lixed contact of the switch and of the circuit breaker being mounts in one housing part and a movable contact of the switch and of the circuit breaker being mounted in the other housing part.

References Cited inthe le of this patent UNTED STATES PATENTS 548,599 Valley Oct. 22, 1895 708,724 Merrick et al. Sept. 9, 1902 1,563,160 Catlin Nov. 24, 1925 1,872,122 Cook Aug. 16, 1932 2,086,709 Pike et al July 13, 1937 2,131,800 Frank Oct. 4, 1938 FOREIGN PATENTS 613,306 Germany May 16, 1935 

